Internal combustion engines



June 16, 1959 Filed 001;. 28, 1953 J. R. GOIOT 2,890,688

INTERNAL COMBUSTION ENGINES 2 Sheets-Sheet 1 June 16, 1959 J. R. GOIOTINTERNAL COMBUSTION ENGINES 2 Sheets-Sheet 2 Filed Oct. 28, 1953 u w Q..

INTERNAL C@USTiN ENGINES Jean Roger Goiot, Nantes, France ApplicationOctober 28, 1953, Serial No. 388,752

Claims priority, application France December 4, 1952 Claims. (Cl.123-48) The present invention relates to a spark operated two strokecombustion engine. In spark operated two-stroke engines it is usual toadopt a high volumetric compression ratio and this necessitates, on theone hand, the provision of a very powerful ignition device to overcomethe resistance of the overcompressed air, and, on the other hand, theprovision of a crankshaft with a fly wheel having a great reserve ofinertia to ensure the provision of the necessary compression when theengine turns at low speed.

It has been found that engines running at low speeds, even when equippedwith such means, operate irregularly and with some roughness; in thecase of a two-stroke engme, in particular, this irregularity involves aserious drawback which consists in that the engine shows, at low speed,a tendency to operate according to the four stroke cycle method.

The invention has for its object to overcome this drawback in a sparkoperated two stroke engine.

According to the present invention a spark operated two-stroke internalcombustion engine having a high compression, comprises an auxiliarychamber connecta-ble with the main combustion chamber by means of avalve which through a mechanical, pneumatical, hydraulical orelectromagnetical connection is controlled by a member controlling theengine over its whole working range, the said connection beingcontrolled by said member in such a manner that when such member ismoved to the position which corresponds to slow running of the enginethe said connection causes the opening of the valve, while as soon asthe control member is removed from its slow running position the saidconnection causes the closure of the valve.

On account of this mode of connection in which the auxiliary chamber isautomatically connected to the combustion chamber by bringing the saidcontrol member into its position which corresponds to slow runningcondition, the volumetric compression ratio is reduced and ensures asmooth running of the engine. Furthermore as at slow running conditionsthe compression ratio is reduced it is possible to reduce the size ofthe fly-wheel together with the power of the ignition device.

By way of example several forms of embodiment of the object of theinvention are described hereafter and illustrated in the annexeddrawing, in which:

Figure 1 illustrates partly, in diametral section, the upper part of acylinder in the carter of which has been provided the auxiliary chamber.

Figure 2 is a view similar to the View of Figure l, the valve mountedbetween the cylinder of the engine and the auxiliary chamber being shownas lifted from its seat, and

Figures 3, 4, 5, 6 illustrate alternative embodiments of the controllover of the valve.

In Figures 1 and 2, the numeral 1 designates the main combustion chamberin the cylinder head 2 into which is also drilled a threaded hole 3 toreceive the spark plug 4.

The cylinder head, preferably in the part adjoining the 2,890,688Patented June 16, 1959 drilling for the spark plug 4, is provided with arecess or pocket 5 covered by means of a cover 6 held in position bysuitable fixing means (not shown). This auxiliary chamber 5 is isolatedfrom the combustion chamber 1 by a socket 7 with a solid bottom 8,screwed or forced into the part 9 of the cylinder head. The bottom 8 ofthe socket is bored with ports ill, 11 opening in the auxiliary chamber5 and its forward lip forms a seat 12 for the head 13 of the valve, thestem 14 of which is guided by a bore 15 in the bottom of the socket 7and extends beyond the boss 16 of the cover 6, passing through astufiing box including a tightening nut 17. This nut 17 includes ahollow portion 18 in which is arranged a compression spring 19surrounding the stem 14 of the valve and bearing, by one of its ends,upon the bottom 20 of this hollow portion and by its other end upon awasher 21 mounted on the stem M and fixed by means of the setpin 22.

On an arm or bracket 23 of the boss 16 is pivoted in 24 a lever 24, thenose 25 of which is near the end 26 of the stem 14, the other end 27 ofthislever being, through mechanical hydraulic, pneumatic orelectromagnetic connection, appropriately connected, for example byknown arrangements.

This connection is carried out so that, when the said member is broughtinto a position which corresponds to slow running condition of theengine, the lever 24 revolves to apply the nose 25 to the end 25 of thestem 14; the stem is thereby pushed towards the combustion chamber andmoves the head 13 of the valve apart from the seat 12, thus permittingthe auxiliary chamber 5 to communicate with the combustion chamber l.The ratio of volumetric compression is thereby reduced and allows theengine running slowly, but it allows, due to the low volumetric ratio,to reduce the size of the flying-wheel and the power of the ignitionequipment.

According to the embodiment of Figure 3, the end 26 of the stem 14 ofthe valve bears upon the surface of a cams 28 mounted on an axis 29, thenose of which is designated by 30. To lift the valve 13 from its seat12, and thereby connect the combustion chamber 1 with the auxiliarychamber 5, the cam is moved from the position shown in Figure 3 to theposition shown in Figure 4, the nose 3% thrusting back the stem 14against the action of spring 19. This rotary motion of the cam isobtained by moving the member controlling the engine over its wholeworking range, for example the throttle control lever or handle into itsposition which corresponds to the slow running condition of engine. Forthat purpose, the handle or lever will, when brought to a position whichcorresponds to slow running condition, actuate a Bowden wire, which inturn will act, in any suitable manner, on the cam 28, to bring this caminto a position corresponding to Figure 4. According to an alternativeembodiment, the cam 23 can be driven directly by the Bowden cablecontrolling the fuel supply on motorcycles; the wire will rotate theshaft of the cam when the lever or twist grip of the motor-cyclecontrolling the fuel supply is actuated, and in this case thecylindrical surface of the cam will correspond to the normal or fastworking conditions of the engine while the peripherical length of thenose corresponds to the slow running conditions. Instead of the Bowdenwire for actuating the lever 24' or the cam 28, one can use a system ofrods, slidably arranged or connected to each other by means of'bellcrank levers.

In the alternative embodiment of Figure 5, the end 26 of the stem 14 ofthe valve is operated for the opening of the valve 13 by means of anhydraulic device including a first cylinder 31 in which is arranged apiston 32 on which acts a spring 33, the rod 34 of this piston being inalignment with the stem 14 of the valve 13. The cylinder 31 is connectedby a duct 35 with a 3 second cylinder 36 in which slides the piston 37,the rod 38 of which is operated by one of the above said control memberscontrolling the engine of its whole working range. The chambers 39, 40of the cylinders 36, 31 and the duct 35 are filled up with anincompressible liquid which transmits the stress F generated by piston37 to the piston 32 which is thereby pressed back towards the right andcauses, through the rod 34, the opening of the valve 13 as soon as oneof the said control members is moved into its position which correspondsto the slow running position of the engine.

In the form of embodiment of Figure 6, the stem 14 of the valve 13 ispressed back in the position giving rise to the opening of the valve 13by means of a lever 24', arranged as in Figure l but operated by anelectro magnetic device. For this purpose, the magnetic core 39 of anelectro magnet 39 is hinged at 27 on lever 24 pivoting around the axis24 and having its nose located in front of the end 26 of the stem 14.The electro magnet 39' is fed, for instance, by the dynamo D of theengine and its supply circuit is controlled by a switch 40, the closingof which is synchronized with one of the control members controlling theengine over its Whole working range in such a manner that as soon as oneof such member is brought into a position corresponding to slow runningcondition, switch 40 is closed causing lifting of the valve 13. Theswitch 40 can, for instance, be associated with the throttle lever 41 ofthe engine and will include a fixed contact 42 placed on the path of amovable contact 43 carried by the lever and adapted to close the circuitof the electro magnet When this lever is in the position correspondingto the slow running conditions.

Although the example above described and illustrated shows a singleauxiliary chamber controlled by a single valve, the present inventionincludes also the embodiments including one or several auxiliarychambers, controlled by one or several valves or similar devices.

What I claim is:

1. A spark-operated two-stroke internal combustion engine comprising acylinder, means defining an auxiliary chamber provided with means forcommunicating with said cylinder to reduce the compression ratio in thecylinder, valve means normally closing said communicating means betweenthe cylinder and the auxiliary chamber, and automatic means maintainingthe valve means in position to close said communicating means duringoperation of the engine at high and medium speeds but acting upon saidvalve means to open said communicating means when said engine operatesat low speeds normally resulting in erratic engine operation to opensaid auxiliary chamber into communication with said cylinder at such lowspeeds.

2. A spark-operated two-stroke internal combustion engine as defined inclaim 1, wherein said communicating means between the auxiliary chamberand the cylinder comprises a socket member having a seat for the valvemeans and a plurality of ports of restricted cross section communicatingwith the auxiliary chamber.

3. In a spark operated two-stroke internal combustion engine including agas handle controlling the engine over its whole working range, acylinder, a cylinder head defining therewith a main combustion chamber,a pocket formed in said cylinder head, said pocket being closedoutwardly and communicating with the main combustion chamber by anaperture formed as a valve seat, a valve cooperating with said seat andhaving a stem slidably disposed in said cylinder head, the free end ofthe stem projecting outwardly from the cylinder head spring means actingon said stem and thereby applying the valve against the seat duringnormal working condition of the engine, a cam rotatably mounted adjacentthe free end of the stem, a peripheral nose on said earn, a Bowden cableoperatively connecting the gas handle and the cam to cause, as soon asthe said gas handle is brought into its position which corresponds toslow working condition of the engine, rotation of the cam in a directionbringing the nose thereof in contact with the free end of the stemwhereby the valve is unseated and allows free communication of the maincombustion chamber and the pocket, while as soon as the gas handle isremoved from its position which corresponds to slow working condition ofthe engine, the cam is rotated in the reverse direction whereupon thevalve is seated on account of the action of the spring.

4. A spark-operated two-stroke internal combustion engine as defined inclaim 1 in which the automatic means are controlled by a Bowden cable.

5. In a spark-operated two-stroke internal combustion engine including athrottle lever controlling the engine over its whole working range, acylinder, a cylinder head defining therewith a main combustion chamber,a pocket formed in said cylinder head, said pocket being closedoutwardly and communicating with the main combustion chamber by anaperture formed as a valve seat, a valve cooperating with said seat andhaving a stem slidably disposed in said cylinder head, the free end ofsaid stem projecting outwardly from the cylinder head, spring meansacting on said stem and thereby applying the valve against the seatduring normal working condition of the engine, a lever pivotedintermediate its ends and having a magnetic core pivotally connected tothe other end of said lever, an electro-magnet arranged in front of saidcore, a current supply circuit for said magnet including a switch, amovable contact carried by the throttle lever and adapted as soon as thethrottle lever is brought into its position which corresponds to slowrunning conditions to close the supply circuit of the electro-magnet andto actuate the core whereby the pivoted lever is rotated in a directionto act upon the free end of the stem and to unseat the valve whichallows free communication of the main combustion chamber and the pocket,while as soon as the throttle lever is removed from its position whichcorresponds to slow working conditions of the engine, the switch returnsin its inoperative position allowing the closure of the valve on accountof the action of the spring.

References Cited in the file of this patent UNITED STATES PATENTS983,150 Leoni Ian. 31, 1911 1,134,967 Brownlee et al. Apr. 6, 19151,925,086 Snyder Sept. 5, 1933 2,042,969 Snyder June 2, 1936 2,094,266Snyder Sept. 28, 1937 2,120,290 Meyer June 14, 1938 2,142,950 LoefflerJan. 3, 1939

